I am not in soCal, so can't help you with a short term rental.
You should know that the rear bench seat is a very rough ride and is OK for short distances, but I would not want to travel more than 1-2 hours back there. While the rear bench does have seat belts anchored properly, there are no headrests and the clearance to the back doors is very short.
There is a known issue with the seat belts on the second row captains chairs because they are anchored to the seats vs the floor. If these seating issues are a concern to you, the E-Trek won't work well for a family of 5 for any extensive travel. We use all 7 seats for short excursions to trailheads or tailgating.
Not sure how 5 people would sleep. I assume it would include taking along a tent for expansion space. On a rainy day it gets cozy with just 2 adults inside.
Other than these questions I would expect that an E-Trek would work well if you used it within it's design constraints.
